1. Field of the Invention
The present invention relates to a compact imaging lens assembly, and more particularly, to an imaging lens assembly for compact camera modules.
2. Description of the Prior Art
In recent years, with the popularity of camera modules, the demand for compact imaging lenses is increasing, and the sensor of a general photographing camera is none other than CCD (charge coupled device) or CMOS sensor (Complementary Metal Oxide Semiconductor Sensor). Furthermore, the pixel size of sensors is reduced due to the advancing semiconductor manufacturing technology and makes electronic products become more compact and powerful. Therefore, there is an increasing demand for compact imaging lenses with superb image quality.
A conventional compact imaging lens is generally configured as a three-lens element structure for the purpose of aberration correction, which a positive-negative-positive Triplet structure is usually adopted. When the lens continues to reduce in size, imaging space in the system also reduces. Thus, the insertion of three lens elements becomes difficult, and within a limited space, the thickness of the lens also decreases, which causes unevenness of the plastic lens material from injection molding process.
In order to effectively reduce the total track length of the lens assembly while maintaining high yield in lens manufacturing, two-lens structure proves to be the best solution. For the purpose of correcting aberrations, usually an arrangement of frontal aperture stop is adopted, such as a compact imaging lens assembly comprising two lens elements disclosed in U.S. Pat. No. 7,525,741. However, a frontal aperture stop setup will generate too much unwanted light entry, which increases the sensitivity of the optical system, and ultimately makes it difficult to control the yield in manufacturing process.
Therefore, a need exists in the art for a compact imaging lens assembly that requires simple manufacturing process, without total track length of the system being too long and the system sensitivity being too high.